JP2003173939A - Method of manufacturing solid-state electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a solid-state electrolytic capacitor in which conductive high-molecular compound is used as a cathode material, which enables the solid-state electrolytic capacitor to reduce a leakage current and a occurrence rate of a current leakage failure. <P>SOLUTION: A solid-state electrolytic capacitor is manufactured through a method where a dielectric oxide film 3 is made to serve as an anode, and a solid-state electrolytic layer 4 is formed on the dielectric oxide film 3 to serve as a cathode. After or while the solid-state electrolytic layer 4 is formed, the electrolytic layer 4 including the dielectric oxide film 3 is dipped into an inorganic acid aqueous solution or an organic acid aqueous solution 8, the plus side of a step-up power supply 9 is connected to an anode leading wire 2, on the other hand, the inorganic acid aqueous solution or an organic acid aqueous solution 8 is connected to the minus side of the step-up power supply 9, a DC positive voltage is applied and stepped up at a certain rate, a solid-state electrolytic layer on the defective part of the dielectric oxide film 3 is locally, electrically insulated to form a solid-state electrolytic layer 4 serving as a cathode layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive polymer as a solid electrolyte.

[0002]

2. Description of the Related Art As is well known, a solid electrolytic capacitor has a porous molded body of valve-acting metal such as tantalum or aluminum as an anode, an oxide film of the metal as a dielectric, and manganese dioxide on the surface of which is highly conductive. A solid electrolyte such as molecules is formed, and the solid electrolyte is used as a cathode.

To further explain, referring to FIG. 3, the solid electrolytic capacitor has an oxide film 3 serving as a dielectric and a conductive film formed on the surface of a valve metal body 1 made of aluminum, tantalum, niobium, titanium or the like having an anode lead wire 2. A solid electrolyte layer 4 which is a conductive polymer compound layer, a carbon layer 5 which is a conductor layer which becomes a cathode, and a silver paste layer 6 are sequentially formed and are sealed with an exterior resin (not shown).

By the way, according to the conventional manufacturing method of the solid electrolytic capacitor having such a structure, the valve action metal compact 1 having the oxide film 3 formed thereon is alternately dipped in the conductive polymer monomer solution and the oxidizing agent solution. Or the solid electrolyte layer 4 by immersing in a mixed solution of a monomer solution and an oxidant solution and drying.
And a constant voltage application process was performed twice after the formation work of the solid electrolyte layer 4 was performed using the phosphoric acid aqueous solution and after the formation of the solid electrolyte layer 4 was completed.

[0005]

However, in this conventional method, the oxide film 3 serving as a dielectric is not uniformly formed, and the solid electrolyte layer 4 which is a conductive polymer compound layer is formed on the oxide film 3 by chemical oxidative polymerization. When formed, this solid electrolyte layer 4 is also formed in the defective portion of the oxide film 3, and there is a problem that that portion becomes a conductive portion and the leakage current increases, and during formation of the solid electrolyte layer 4. , A constant voltage is applied after formation, or both, the equivalent series resistance (ES
There is a problem that R) becomes large.

The present invention has been made in view of the above conventional problems, and an object thereof is to prevent leakage current of a solid electrolytic capacitor using a conductive polymer compound obtained by chemical polymerization as a cathode material. To reduce.

[0007]

To this end, the invention according to claim 1 provides a solid electrolytic capacitor having a dielectric oxide film as an anode and a solid electrolyte layer formed on the dielectric oxide film as a cathode. In the manufacturing method, during or after the formation of the solid electrolyte layer, a direct current positive voltage is applied at a constant rate while immersing the dielectric oxide film so as to be submerged in the inorganic acid aqueous solution or the organic acid aqueous solution. The solid electrolyte layer on the defective portion of the dielectric oxide film is locally insulated to form a solid electrolyte layer which is a cathode layer by treatment.

The invention according to claim 2 is characterized in that the dielectric oxide film has a valve metal such as aluminum, tantalum, niobium, or titanium as an anode, and the oxide film as a dielectric.

The invention according to claim 3 is characterized in that the solid electrolyte layer is a conductive polymer compound layer formed by chemically polymerizing a conductive polymer such as polypyrrole, polythiophene, and polyaniline.

The invention according to claim 4 is characterized in that the inorganic acid aqueous solution is an acidic aqueous solution containing nitric acid, phosphoric acid or a salt thereof.

According to a fifth aspect of the invention, the aqueous solution of organic acid is an aqueous solution of a compound having an acidic functional group such as oxo acid except inorganic acid and carboxylic acid, sulfonic acid, sulfinic acid, acid amide, oxime, sulfonamide. It is characterized by being.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described. The method for manufacturing a solid electrolytic capacitor according to the present invention,
In the method for manufacturing a solid electrolytic capacitor in which the dielectric oxide film 3 is used as an anode and the solid electrolyte layer 4 formed on the dielectric oxide film 3 is used as a cathode, as shown in FIG.
During the formation of the solid electrolyte layer 4 of the conductive polymer compound which is the cathode layer, or after the formation or both of the formation and the formation of the dielectric oxide film 3 up to the portion of the acid aqueous solution tank 7 in the inorganic acid aqueous solution or the organic acid. Valve action metal molded body 1 so as to be submerged in the aqueous solution 8
While soaking, step up power supply 9 to anode lead wire 2
Of the inorganic acid aqueous solution or the organic acid aqueous solution 8 side is the negative side, and a direct current positive voltage is applied at a constant rate by pressurizing and applying the solid electrolytic layer on the defective portion of the dielectric oxide film 3. The solid electrolyte layer 4 is locally insulated to form the solid electrolyte layer 4, thereby reducing the leakage current.

There are two methods for forming the solid electrolyte layer 4. As one method, FIG.
As shown in the formation flow sheet of (a), the valve action metal compact 1 on which the oxide film 3 is formed is dipped in the monomer solution, dried, and then dipped in the oxidant solution and dried.
This is repeated several times to form the solid electrolyte layer 4 which is a conductive polymer compound layer. As another method, as shown in the formation flow sheet of FIG. 2B, the valve action metal molded body 1 having the oxide film 3 formed thereon is dipped in a mixed solution of a monomer solution and an oxidant solution, The solid electrolyte layer 4 which is a conductive polymer compound layer is formed by drying and repeating this several times.

[0014]

EXAMPLES Specific examples of the present invention will be described below. Example 1 After the dielectric oxide film 3 was formed on the surface of the valve metal molding 1, and the solid electrolyte tank 4 was formed once on the dielectric oxide film 3, the dielectric oxide film 3 part was formed. While immersing the valve action metal molded body 1 so as to be immersed in the 0.01 to 2.0 wt% phosphoric acid aqueous solution 8 in the acid aqueous solution tank 7, the positive side of the step-up power source 9 is connected to the anode lead wire 2. On the other hand, the voltage treatment is set to 1 with the phosphoric acid aqueous solution 8 side as the negative side.
I went there. In the voltage treatment at this time, the voltage was raised to a predetermined voltage at 0.1 to 1.0 V per minute and then held for 5 to 15 minutes. After that, the solid electrolyte layer 4 was continuously formed, and the solid electrolytic capacitor was completed based on the description in Paragraph No. 0003.

Example 2 After the dielectric oxide film 3 was formed on the surface of the valve metal molding 1, and the solid electrolyte tank 4 was formed on the dielectric oxide film 3, the dielectric oxide film 3 was reached. A voltage treatment was performed in the same manner as in Example 1 while immersing the valve action metal compact 1 so as to be submerged in the 0.01 wt% paratoluenesulfonic acid aqueous solution 8 in the acid aqueous solution tank 7. Then, the solid electrolytic capacitor was completed in the same manner as in Example 1.

Example 3 A dielectric oxide film 3 was formed on the surface of the valve metal molding 1, and after the solid electrolyte tank 4 was formed on the dielectric oxide film 3, the dielectric oxide film 3 was reached. Voltage treatment was performed while immersing the valve action metal molded body 1 so as to be submerged in the 0.01 to 2.0 wt% phosphoric acid aqueous solution 8 in the acid aqueous solution tank 7.
Then, the solid electrolytic capacitor was completed in the same manner as in Example 1.

Example 4 After forming the dielectric oxide film 3 on the surface of the valve action metal molded body 1 and forming the solid electrolyte tank 4 on the dielectric oxide film 3, the dielectric oxide film 3 is reached. Voltage treatment was performed while immersing the valve action metal molded body 1 so as to be submerged in the 0.01 wt% paratoluenesulfonic acid aqueous solution 8 in the acid aqueous solution tank 7. Then, the solid electrolytic capacitor was completed in the same manner as in Example 1.

Example 5 After the dielectric oxide film 3 was formed on the surface of the valve metal molding 1, and the solid electrolyte tank 4 was formed once on the dielectric oxide film 3, the solid oxide tank 3 was formed. 2 after the formation of 4
In the operation, the acid aqueous solution tank 7 up to the part of the dielectric oxide film 3
While the valve action metal molded body 1 was dipped so as to be submerged in the 0.01 to 2.0 wt% phosphoric acid aqueous solution 8, the voltage treatment was performed twice. Then, the solid electrolytic capacitor was completed in the same manner as in Example 1.

Example 6 After the dielectric oxide film 3 was formed on the surface of the valve action metal compact 1 and the solid electrolyte tank 4 was formed once on the dielectric oxide film 3, the solid oxide tank 3 was formed. 2 after the formation of 4
In the operation, the acid aqueous solution tank 7 up to the part of the dielectric oxide film 3
While the valve action metal molded body 1 was dipped so as to be submerged in the 0.01 wt% paratoluenesulfonic acid aqueous solution 8, the voltage treatment was performed twice. Then, the solid electrolytic capacitor was completed in the same manner as in Example 1.

Next, as a reference example, a solid electrolytic capacitor was completed without performing voltage treatment when forming the solid electrolyte layer 4.

Examples 1 to 6 and Reference Example, the paragraph number 0
For each solid electrolytic capacitor of the conventional example described in 004, the result of comparing the leakage current defective rate, the median of the measured values of the leakage current when the rated voltage is applied, and the average value of the equivalent series resistance (ESR) are shown in Table 1. Show.

[0022]

[Table 1]

As is clear from Table 1, the solid electrolytic capacitor obtained by the method of the present invention in which the voltage treatment is performed during and after the formation of the solid electrolyte layer can reduce the leakage current, and has an equivalent series resistance (ESR). It can be seen that a solid electrolytic capacitor having excellent characteristics was obtained.

Further, it has been found that, as in the conventional example, by stepping up from a low voltage in steps rather than applying a constant voltage, the effect of reducing the leakage current, the leakage current defect rate, and the equivalent series resistance is higher. .

[0025]

As described above, according to the present invention, it is possible to provide a solid electrolytic capacitor having a small leakage current and a low occurrence rate of leakage current defects, and having excellent equivalent series resistance (ESR) characteristics. . This means that the solid electrolyte on the defective portion of the dielectric oxide film layer is locally insulated by voltage treatment in view of the behavior of the leakage current during the voltage treatment in the acid aqueous solution, and the solid electrolyte layer is also treated. This is because by performing voltage treatment twice during and after the formation, leakage current defects can be further reduced, and step-up boosting can suppress heat generation due to leakage current and enable more localized insulation. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating a voltage treatment for forming a solid electrolyte layer in the present invention.

FIG. 2 is a flow sheet for forming a solid electrolyte layer in a solid electrolytic capacitor. (A) is a flow sheet of one method. (B) is a flow sheet of another method.

FIG. 3 is a schematic cross-sectional view showing the basic structure of a solid electrolytic capacitor.

[Explanation of symbols]

1 Valve action metal compact 2 Anode lead wire 3 oxide film 4 Solid electrolyte layer (conductive polymer compound layer) 5 carbon layer 6 Silver paste layer 7 Acid solution tank 8 Acid aqueous solution 9 step boost power supply

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshikatsu Terao             Niemon, Fukuchi Village, Sannohe-gun, Aomori Prefecture             No. 3 Mountain Tohoku Media Device Co., Ltd.             Within

Claims (5)

[Claims] 1. A method of manufacturing a solid electrolytic capacitor, wherein a dielectric oxide film serves as an anode and a solid electrolyte layer formed on the dielectric oxide film serves as a cathode, wherein during or after the formation of the solid electrolyte layer, A solid electrolyte layer on the defective portion of the dielectric oxide film is applied by applying a positive DC voltage at a constant rate while immersing the dielectric oxide film so as to be immersed in an inorganic acid aqueous solution or an organic acid aqueous solution. A method for producing a solid electrolytic capacitor, which comprises locally insulating a solid electrolyte layer as a cathode layer. 2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the dielectric oxide film has a valve action metal such as aluminum, tantalum, niobium, or titanium as an anode and the oxide film as a dielectric. 3. The method for producing a solid electrolytic capacitor according to claim 1, wherein the solid electrolyte layer is a conductive polymer compound layer formed by chemically polymerizing a conductive polymer such as polypyrrole, polythiophene and polyaniline. 4. The method for producing a solid electrolytic capacitor according to claim 1, wherein the inorganic acid aqueous solution is an acidic aqueous solution containing nitric acid, phosphoric acid or a salt thereof. 5. The solid solution according to claim 1, wherein the organic acid aqueous solution is an aqueous solution of a compound having an acidic functional group such as oxo acid excluding inorganic acid and carboxylic acid, sulfonic acid, sulfinic acid, acid amide, oxime, sulfonamide. Method for manufacturing electrolytic capacitor.